Potato cultivars use distinct mechanisms for salt stress acclimation

Soil salinity induces osmotic stress and ion toxicity in plants, detrimentally affecting their growth. Potato (Solanum tuberosum) suffers yield reductions under salt stress. To understand salt-stress resilience mechanisms in potatoes, we studied three cultivars with contrasting salt sensitivity: Innovator, Desirée, and Mozart. Innovator emerged as the most resilient under salt stress, displaying minimal reductions in growth and plant tolerance index with no tuber yield loss, despite notable water loss. Conversely, Desirée experienced a significant tuber yield reduction but maintained better water retention. Mozart showed a low plant tolerance index and high water loss. Interestingly, ions measurement across different tissues revealed that, unlike chloride, sodium does not accumulate in tubers under salt stress in these cultivars, suggesting existence of an active sodium exclusion mechanism. A whole root transcriptomic analysis of these cultivars revealed a conserved salt stress response between potato and Arabidopsis. This response includes activation of various abiotic stress pathways and involves sequential activation of various transcription factor families. Root analyses showed that Innovator has lower suberin and lignin deposition, along with stronger K⁺ leakage in control conditions, resulting in a higher early stress response and increased ABA accumulation shortly after salt stress induction. This could explain Innovator has a more divergent transcriptomic response to salt stress compared to Desirée and Mozart. Nevertheless, Innovator displayed high suberin and lignin levels and ceased K⁺ leakage after salt stress, suggesting a high acclimation ability. Altogether, our results indicate that acclimation ability, rather than initial root protection against salt prevails in long-term salt-stress resilience of potato.